Tuning the nuclearity of [MoOS]-based assemblies by playing with the degree of flexibility of bis-thiosemicarbazone ligands.

[MoV2OS]-based thiosemicarbazone complexes appear as very promising molecules for biological applications due to the intrinsic properties of their components. This paper deals with the synthesis and characterization of six coordination complexes obtained by the reaction of [MoV2OS] clusters with bis-thiosemicarbazone ligands that contain flexible or rigid spacers between the two thiosemicarbazone units. Interestingly, structural characterization by single-crystal X-ray diffraction, MALDI-TOF MS technique and NMR spectroscopy revealed that the nuclearity of the complex is controlled by the nature of the spacer between the thiosemicarbazone units. Binuclear complexes, namely [MoV2OS(L)], are isolated with flexible spacers while tetranuclear complexes [(MoV2OS)(L)] are formed when the bis-thiosemicarbazone ligands are built on rigid spacers.